Quick coupling means for a working implement of an excavating machine

ABSTRACT

A coupling means for detachably coupling a working implement to the operating arm of an excavating machine, said implement having an upper surface facing the operating arm, said coupling means comprising a first attachment member which is rigidly mounted to the upper surface of the implement and comprises a coupling element, and a second attachment member supported by the operating arm stick and operating cylinder via horizontal, parallel shafts and comprising a coupling element consisting of two locking parts arranged movable in relation to each other to be brought into locking engagement with the coupling element of the first attachment member by means of a power-generating means, said coupling elements having cooperating engagement surfaces which when the attachment members are connected together, are located in a common reference plane which is perpendicular to a common central plane for a stick and operating cylinder. In accordance with the invention all engagement surfaces of the two coupling elements have a circle arc-shaped extension in said reference plane and have the same radius.

The present invention relates to a coupling means for detachablycoupling a working implement to the operating arm of an excavatingmachine, said implement having an upper surface facing the operatingarm, said coupling means comprising a first attachment member which isrigidly mounted to the upper surface of the implement and comprises acoupling element, and a second attachment member supported by theoperating arm stick and operating cylinder via horizontal, parallelshafts and comprising a coupling element consisting of two locking partsarranged movable in relation to each other to be brought into lockingengagement with the coupling element of the first attachment member bymeans of a power-generating means, said coupling elements havingcooperating engagement surfaces which, when the attachment members areconnected together, are located in a common reference plane which isperpendicular to a common central plane for the stick and operatingcylinder.

The object of the present invention is to provide an improved couplingmeans which allows the attachment members to be connected in such amanner that the working implement can assume at least two differentpositions in relation to the operating arm and which, besides a frictionjoint, provides a form joint which prevents the attachment members frombeing displaced laterally in relation to each other in the common planeof the attachment members, either in connected position or when thefriction joint has been released or not yet been brought into operation,while the coupling element of the operating arm is in loose but notseparable engagement with the coupling element of the implement.

It is a further object of the present invention to provide a couplingmeans enabling the attachment members to be connected without theimplement and its attachment members having to be placed and aligned toeach other in any special coupling position.

A still further object of the present invention is to provide a couplingmeans enabling the attachment members to be connected in such a mannerthat the working implement can assume an unlimited number of differentpositions in relation to the operating arm.

A further object of the present invention is to provide a coupling meansenabling the implement to be turned in relation to the operating armwhile the attachment members are in loose but inseparable engagementwith each other. The implement can thus be connected to the operatingarm irrespective of how it is placed on the ground. A first connectioncan thus be achieved immediately, after which the implement can be movedcloser to the excavator or to a more suitable place in front of thismachine. If the friction joint is released but the form joint retained,the implement can be turned in relation to the attachment members of theoperating arm, until the implement assumes the correct position for thework desired. This turning movement is enabled by a lower corner of theimplement being brought into abutment with a suitable counter support onthe ground. During excavation work, for instance, the implement can thusbe directed in a different direction, thereby making more expedient usethereof for a specific task, e.g. excavating or levelling out materiallaterally.

A further object of the present invention is to provide a coupling meanshaving an attachment member for the implement so designed that it can bewelded onto the implement without time-consuming and accurate alignmentof the coupling means.

The above mentioned objects are achieved by the coupling means accordingto the present invention which is substantially characterised in thatall engagement surfaces of said two coupling elements have a circlearc-shaped extension in said reference plane and have the same radius.

In the most preferred embodiment of the invention the engagementsurfaces are arranged in relation to each other in such a manner thatthey have the same centre when the attachment members are connectedtogether.

Additional features, advantages and objects of the invention will beapparent from the following description and claims.

The invention will be described further in the following, with referenceto the accompanying drawings.

FIG. 1 shows schematically parts of a bucket and operating arm of anexcavating machine seen from the side, the bucket being pivotably andcontrolably journalled to the operating arm via a coupling meansaccording to a first embodiment of the present invention.

FIG. 2 is a plan view of the coupling means according to FIG. 1 with itstwo attachment members connected together.

FIG. 3 shows the operating arm attachment member in a top view with theupper side pieces removed for the sake of clarity.

FIG. 4 shows the bucket attachment member seen from the side.

FIG. 5 shows parts of the two attachment members of the coupling meanswhen connected together.

FIG. 6 is a cross section of the attachment members along the lineVI--VI in FIG. 2.

FIG. 7 shows schematically parts of a bucket and operating arm of anexcavating machine seen from the side, the bucket being pivotably andcontrolably journalled to the operating arm via a coupling meansaccording to a second embodiment of the present invention.

FIG. 8 is a plan view of the coupling means according to FIG. 7 with itstwo attachement members connected together.

FIG. 9 is a vertical diametrical section through the bucket attachment.

FIG. 10 shows parts of the two attachment members of the coupling meanswhen connected together.

FIG. 11 is a central cross section through the attachment membersaccording to FIG. 8.

With reference to FIG. 1, it is shown therein in a side view a workingimplement in the form of a bucket 1 for an excavating machine. Thebucket has a flat top portion 2 with a rear edge 3 and a front edge 4which is close to the bucket opening 5. The operating arm of theexcavator comprises a stick 6 and a hydraulic operating cylinder 7arranged on the front side of the operating arm (the side facing awayfrom the excavator). The stick 6 is provided with a horizontal bolt orshaft 8 at its lower, free end. Similarly, the hydraulic operatingcylinder 7 is provided at its lower free end with a horizontal bolt orshaft 9 which is parallel to the shaft 8 of the stick 6 and is locatedin front of this.

The operating arm 6, 7 of the excavator and the bucket 1 are connectedto each other by a coupling means in the form of a quick coupling inaccordance with the present invention. The bucket is pivotably supportedby the shaft 8 of the stick 6 and this shaft thus forms the pivotingcentre of the bucket. A controlled pivoting movement of the bucket aboutthe shaft 8 of the stick 6 is obtained with the aid of the hydraulicoperating cylinder 7.

In the embodiment shown the hydraulic operating cylinder 7 is journalleddirectly at the quick coupling by its piston rod 10 via the shaft 9.Alternatively this journalling can be effected indirectly with the aidof intermediate links.

The quick coupling according to the invention comprises a firstattachment member 11 for the bucket 1 and a second attachment member 12for the operating arm. The attachment member 11 comprises a couplingelement 13 and a distance element 14, by means of which the attachmentmember 11 is welded to the flat top portion 2 of the bucket 1. In theembodiment shown the distance element 14 is in the form of a ring. Thering 14 and coupling element 13 are rigidly connected to each other toform a rigid unit. In the embodiment shown, the coupling element is inthe form of a flat, circular plate provided on the upper side facingaway from the ring 14, with a flat support element 45 which may consistof a single circular piece or of several arc-shaped pieces, so-calledshims. Alternatively, the coupling element may be in the form of a flat,relatively wide ring. The plate 13 (or alternatively the ring) has acircular engagement portion 16 with, in relation to the plane of theplate, an inclined, outwardly directed, circular engagement surface 17having a predetermined radius. The engagement surface 17 facesdownwards, i.e. towards the top portion 2 of the bucket 1. Theengagement surface 17 and the plane envelope an acute angle which canvary in size in a wide range and is preferably between 20° and 60°, mostpreferably between 25° and 35°.

The attachment member 12 for the operating arm comprises a connectingelement 47 forming a rigid body and having substantially U-shaped crosssection. The connecting element is formed of a bottom plate 18 and twoside pieces 19, 20 spaced a predetermined distance apart. The distancebetween the side pieces 19, 20 is determined by the width of the stick 6at its lower end, and the side pieces are provided with axially alignedbushings 46 through which the shafts 8 and 9 pass and in which they arejournalled. The side pieces 19, 20 with bushings 46 are normally weldedin place but have been removed in FIG. 3 for the sake of clarity. Theconnecting element 47 is symmetrical with respect to its verticalcentral plane C_(F) (FIG. 3). The attachment member 12 also includes acoupling element 15 consisting of two locking parts 21, 22 located at adistance from and opposite each other. The locking parts 21, 22 aremovable in relation to each other in order to be brought into lockingengagement with the coupling element 13 of the first attachment member11. One of the locking parts is preferably stationary in relation to theconnecting element 47 whereas the other is movable, thus forming astationary locking part 21 and a movable locking device 22. The lockingpart 21 and locking device 22 are diametrically aligned and symmetricalwith respect to the central plane C_(F) of the connecting element 47.The stationary locking part 21 of the coupling element 15 is arranged onthe side of the connecting element 47 which is located below the shaft 8of stick 6. The locking part 21 is rigidly secured to the bottom plate18 and extends at its lower side 23. It is provided with an engagementportion 24 with an engagement surface 25 facing inwardly and inclinedwith respect to the bottom plate 18. The engagement portion 24 and itsengagement surface 25 have circle arc-shaped extension and encompass asector angle of about 90° in the embodiment shown.

The locking device 22 located diametrically in relation to theengagement portion 24 (or the locking part 21) is provided with anengagement portion 26 located on the lower side of the bottom plate 18and having an inwardly directed engagement surface 27 which is inclinedin relation to the bottom plate 18. The engagement portion 26 and itsengagement surface 27 also have circle arc-shaped extension andencompass a sector angle less than that of the engagement portion 24 andits engagement surface 25, e.g. 20°. The engagement surfaces 25, 27 ofthe locking element 21 and locking device 22 have the same predeterminedradius. This radius agrees with the radius of the engagement surface 17of plate 13. The engagement surfaces 25, 27 form an acute angle with theplane of the bottom plate 18, this angle lying within the ranges statedfor the engagement surface 17 of plate 13. In order to achieve the bestpossible friction joint, the angles of engagement surfaces 17, 25 and 27are the same in each specific case. The locking device 22 is providedwith a straight, upper plate 28 which is arranged to rest on the upperside 29 of the bottom plate 18 of the connecting element 47 and which isconnected to the engagement portion 26 to form a unitary piece withthis. The locking device 22 is arranged to be moved in a rectilinearpath coinciding with the centre line of the connecting element 47, themovement occurring in sliding contact with the upper side 29 of thebottom plate 18, between an outer, free-running position and an inner,locking position in relation to the engagement surface 27 of the plate13. The locking device 22 is guided by a support 31 welded adjacent tothe edge region of the upper side 29 of the bottom plate 18, saidsupport having a rectangular opening somewhat larger than the crosssection of the plate 28 to allow it to move to and fro. The movement ofthe locking device 22 is effected by means of a power-generating means32 via a specially designed link mechanism 33. The power-generatingmeans in the example shown consists of a hydraulic cylinder attached byits rear end to the bottom plate 28 inside the position for the counterpart 21 and close to the side piece 20. The link mechanism 33 comprisesa pressure cam 34 which is rotably connected to the piston rod 35 of thehydraulic cylinder 32 via a vertical pin 36. The pressure cam 34 isdrop-shaped, the larger circular part 37 thereof having opposingvertical circle arc-shaped support surfaces 38, 39. The pressure cam 34is pivotably connected to the plate 28 of the locking device 22 by meansof a vertical pin 40 which is held in position by a locking pin 41. Atthe free end of the plate 28 there is a support 42 with a vertical,transverse, straight support surface 43 located parallel to acorresponding vertical, transverse, straight support surface 44 of thesupport 31. The opposing support surfaces of the circular portion 37 ofthe pressure cam 34 press alternately against the support surface 44 ofthe support 31 and the support surface 43 of the support 42 when thelocking device 22 is moved into the locking position and out to thefree-running position, respectively. By the action of the hydrauliccylinder 32 the pressure cam 34 constantly exerts pressure on thesupport surface 44 of the support 31 when the locking device 22 and thelocking part 21 functioning as counter member are in engagement with theCoupling element 13, a firm and play-free joint is ensured and brakingforces and other forces occurring in the bucket during the work will betransferred to the stick 6 via the coupling element 13, locking element21, locking device 22, link mechanism 33, support 31, connecting element47 and stick shaft 8.

To prevent the coupling grip from being completely lost if a faultoccurs in the hydraulic system serving the hydraulic cylinder 32, aspecial safety device is arranged to ensure that attachment members 11,12 cannot become separated from each other when such a fault occurs.Such a safety device is then served by a drive system other than saidhydraulic system. The plate 28 may be provided with an inner shoulderfor a catch, for instance, which in safety position acts between theshoulder and support 31. The catch forms the free end of a leverpivotably journalled on the bottom plate 18, said lever being constantlyforced by a spring into the safety position. The other end of the leveris actuated by a hydraulic cylinder or some other power-transmittingmeans in a drive system separate from the main drive system of themachine serving the hydraulic cylinder 32. It is therefore an advantageto have a small space between said shoulder and catch so that thelocking device 22 can be moved radially outwards from the plate 13 ashort distance, corresponding to said space, with the aid of thehydraulic cylinder 32 so that the friction joint is released but astructural joint is still maintained, i.e. the attachment members cannotbe separated from each other as will be described further below. Whenthe friction joint is no longer in function, but the form joint is stillmaintained, it is then possible to turn the attachment members inrelation to each other, whereby the safety device thus guarantees thatthe attachment members are not separated from each other.

In FIGS. 5 and 6 a reference plane is designated with the letter R. Thisplane extends through the two coupling elements 13, 15 when connected,the engagement surfaces 17, 25, 27 thus being pressed together to form amaximum friction joint. This reference plane R is thus parallel to thebottom plate 18 and plate 13, and said angles of inclination for theengagement surfaces 17, 25, 27 are also applicable to said referenceplane R. All engagement surfaces 17, 25, 27 are arranged so that theyhave a circle arc-shaped extension in said reference plane and, asmentioned earlier, thus have the same radius. In the embodiment shown,the engagement surface 17 of coupling element 13 has maximum extension,i.e. 360°. Since the engagement surface 17 has circular extension, i.e.maximum circle arc-shaped extension, all the engagement surfaces 17, 25,27 of the two coupling elements 13, 15 will have the same centre whenthe attachment members 11, 12 are connected together. By way ofclarification it would be noted that said reference plane R isperpendicular to a common central plane through the stick 6 andoperating cylinder 7. This central plane thus coincides with the centralplane C_(F) of the attachment member 12 or connecting element 47 (FIG.3).

The shown attachment members 11, 12 are designed to be connected in sucha manner that the bucket can assume different positions in relation tothe operating arm. Since the attachment member 11 is provided with aplate 13 with circular engagement portion 16, the bucket 1 can assume anunlimited number of different positions for the coupling. Furthermore,the attachment member 11 can be mounted on the bucket without the needfor accurate measurements to ensure that the engagement surfaces arealigned and located at predetermined points in relation to each otherand to the side edges of the bucket.

The oblique, cooperating engagement surfaces 17, 25, 27 provide afriction joint with wedge action when the locking device 22 is broughtinto locking position. Inclined engagement surfaces are thereforepreferred. The circular or circle arc-shaped extension of the inclinedengagement surfaces 17, 25, 27 in turn ensures that a form joint isobtained, preventing the attachment members 11, 12 from being displacedlaterally in relation to each other in said reference plane R andperpendicularly to said central plane C_(F) of the attachment member 12.This form joint is thus maintained not only when the locking device 22is in locking position but also when this has been loosened somewhat,i.e. when the locking device 22 and locking part 21 are in loose but notseparable engagement with the bucket plate 13. While retaining this formjoint, the bucket 1 can now be moved in relation to the stick 6 untilthe bucket has assumed the correct position for the work desired. Thisturning and re-adjustment of the bucket can also be performed duringactual excavation in order to move the bucket to a new position suitablefor a specific work, i.e. excavating or levelling out material inlateral direction. During this turning movement a lower corner of thebucket is brought into abutment with a suitable support on the ground.

The circle arc-shaped extension of the engagement portions 24 and 26 mayvary. In general they may each encompass a sector angle of up to about175°. However, this provides an undesired weight increase of thecoupling. The wider the engagement portions, the better will be theengagement of coupling. A compromise must therefore be made. A preferredsector angle for the engagement portion 24 is about 90°-100° and for theengagement portion 26 about 20°-35°.

In FIGS. 7-11 it is shown another embodiment of a coupling meansaccording to the present invention. With reference to FIG. 7 it is shownin a side view a working implement in the form of a bucket 51 for anexcavator, the bucket having a flat top portion 52 with a rear edge 53and front edge 54 which is close to the bucket opening 55. The operatingarm of the excavator comprises a stick 56 and a hydraulic operatingcylinder 57 arranged on the front side of the operating arm (the sidefacing away from the excavator). The stick 56 is provided with ahorizontal bolt or shaft 58 at its lower, free end. Similarly, thehydraulic operating cylinder 57 is provided at its lower free end with ahorizontal bolt or shaft 59 which is parallel to the shaft 58 of stick56 and is located in front of this.

The operating arm 56, 57 of the excavator, and the bucket 51, areconnected to each other by a coupling means in the form of a quickcoupling in accordance with a second embodiment of the presentinvention. The bucket is pivotably supported by the shaft 58 of thestick 56 and this shaft thus forms the pivoting centre of the bucket. Acontrolled pivoting movement of the bucket about the shaft 58 of stick56 is obtained with the aid of the hydraulic operating cylinder 57.

In the embodiment shown the hydraulic operating cylinder 57 isjournalled directly at the quick coupling by its piston rod 60 via theshaft 59. Alternatively this journalling can be effected indirectly withthe aid of intermediate links.

The quick coupling according to this second embodiment of the inventionalso comprises a first attachment member 61 for the bucket 51 and asecond attachment member 62 for the operating arm. The attachment member61 comprises a coupling element 63 which, in the embodiment shown, is inthe form of a ring with a V-shaped cross section. The ring has a flatmounting portion 83 by means of which the coupling element 63 is weldedto the flat top portion 52 of the bucket 51, and an upwardly directedengagement portion 65 having an inwardly directed, inclined, circularengagement surface 66 with a predetermined radius. The engagementsurface 66 faces downwards, i.e. towards the top portion 52 of thebucket 51, an acute angle being formed between the engagement surface 66and the plane of the ring 63, said angle varying in size in a wide rangebut being preferably between 40° and 80°.

The attachment member 62 for the operating arm comprises a connectingelement 67 forming a rigid body and having substantially U-shaped crosssection. The connecting element is formed of a bottom plate 68 and twoside pieces 69, 70 spaced a predetermined distance apart. The distancebetween the side pieces 69, 70 is determined by the width of the stickat its lower end, and the side pieces are provided with axially alignedbushings 96 through which the shafts 58 and 59 pass and in which theyare journalled. The side pieces 69, 70 with bushings 96 are normallywelded in place but have been removed in FIG. 8 for the sake of clarity.The connecting element 67 is symmetrical with respect to its verticalcentral plane C_(F) (FIG. 8). The attachment member 62 also includes acoupling element 64 consisting of two locking parts 71, 72 located at adistance from and opposite each other. The locking parts 71, 72 aremovable in relation to each other in order to be brought into lockingengagement with the coupling element 63 of the first attachment member61. One of the locking parts is preferably stationary in relation to theconnecting element 67 whereas the other is movable, thus forming astationary locking part 71 and a movable locking device 72. The lockingpart 71 and locking device 72 are diametrically aligned and symmetricalwith respect to the central plane C_(F) of the connecting element 67.The stationary locking part 71 of the coupling element 64 is arranged onthe side of the connecting element 67 which is located below the shaft58 of stick 56. The locking part 71 is rigidly secured to the bottomplate 68 and extends peripherally in the direction downwards. It isprovided with an engagement portion 74 with an engagement surface 75facing outwardly and inclined with respect to the bottom plate 68. Theengagement portion 74 and its engagement surface 75 have circlearc-shaped extension and encompass a sector angle of about 90° in theembodiment shown.

The locking device 72 located diametrically in relation to theengagement portion 74 (or the locking part 71) is provided with anengagement portion 76 located at a level under the bottom plate 68 andhaving an outwardly directed engagement surface 77 which is inclined inrelation to the bottom plate 68. The engagement portion 76 and itsengagement surface 77 also have circle arc-shaped extension andencompass a sector angle less than that of the engagement portion 74 andits engagement surface 75, e.g. 30°. The engagement surfaces 75, 77 ofthe locking element 71 and locking device 72 have the same predeterminedradius. This radius agrees with the radius of the engagement surface 66of engagement portion 65. The engagement surfaces 75, 77 form an acuteangle with the plane of the bottom plate 68, this angle lying within theranges stated for the engagement surface 66 of engagement portion 65. Inorder to achieve the best possible friction joint, the angles ofengagement surfaces 66, 75 and 77 are the same in each individual case.The locking device 72 is provided with a straight, upper plate 78 whichis arranged to rest on the upper side 79 of the bottom plate 68 of theconnecting element 67 and which is connected to the engagement portion76 to form a unitary piece with this. The locking device 72 is arrangedto be moved in a rectilinear path coinciding with the centre line of theconnecting element 67, the movement occurring in sliding contact withthe upper side 79 of the bottom plate 68, between an inner, free-runningposition and an outer, locking position. The locking device 72 is guidedin two supports 80, 81, welded one adjacent to the edge region of theupper side 79 of the bottom plate 68, and the other at a distancetherefrom. The supports 80, 81 have rectangular openings somewhat largerthan the cross section of the plate 78 to allow it to move to and from.The movement of the locking device 72 is effected by means of apower-generating means 82 mounted in a protective housing 97 on thelower side 73 of the bottom plate 68. The power-generating means in theexample shown consists of a hydraulic cylinder attached by its rear endto two lugs 98 protruding from the pressure portion 71, and by itsfront, piston rod end is attached to two lugs 99 protruding from theinside of the locking device 72.

In FIG. 10 a reference plane is designated with the letter R. This planeextends through the two coupling elements 63, 64 when connected, theengagement surfaces 66, 75, 77 thus being pressed together to givemaximum friction. This reference plane R is thus parallel to the bottomplate 68 and said angles of inclination for the engagement surfaces 66,75, 77 are also applicable to the reference plane R. All engagementsurfaces 66, 75, 77 are arranged so that they have a circle arc-shapedextension in said reference plane and, as mentioned earlier, have thesame radius. In the embodiment shown, the engagement surface 66 ofcoupling element 63 has maximum extension, i.e. 360°. Since theengagement surface 66 has circular extension, i.e. maximum circlearc-shaped extension, all the engagement surfaces 66, 75, 77 of the twocoupling elements 63, 64 will have the same centre when the attachmentmembers 61, 62 are connected together. By way of clarification it wouldbe noted that said reference plane R is perpendicular to a commoncentral plane through the stick 56 and operating cylinder 77. Thiscentral plane thus coincides with the central plane C_(F) of theattachment member 62 or connecting element 67 (FIG. 8).

The shown attachment members 61, 62 are designed to be connected in sucha manner that the bucket can assume different positions in relation tothe operating arm. Since the attachment member 61 is provided with aring 63 with circular engagement portion 65, the bucket 51 can assume anunlimited number of different positions for the coupling. Furthermore,the attachment member 61 can be mounted on the bucket without the needfor accurate measurements to ensure that the engagement surfaces arealigned and located at predetermined points in relation to each otherand to the side edges of the bucket.

The oblique, cooperating engagement surfaces 66, 75, 77 provide afriction joint with wedge action when the locking device 72 is broughtinto locking position. Inclined engagement surfaces are thereforepreferred. The circular or circle arc-shaped extension of the inclinedengagement surfaces 66, 75, 77 in turn ensures that a form joint isobtained, preventing the attachment members 61, 62 from being displacedlaterally in relation to each other in said reference plane R andperpendicularly to said central plane C_(F) of the attachment member 62.This form joint is thus maintained not only when the locking device 72is in locking position but also when this has been loosened somewhat,i.e. when the locking device 72 and locking part 71 are in loose butinseparable engagement with the ring 63 of the bucket. While retainingthis form joint, the bucket 51 can now be turned in relation to thestick 56 until the bucket has assumed the correct position for the workdesired. This turning and re-adjustment of the bucket can also beperformed during actual excavation in order to move the bucket to a newposition suitable for a specific work, i.e. excavating or levelling outmaterial in lateral direction. During this turning movement a lowercorner of the bucket is brought into abutment with a suitable support onthe ground.

The circle arc-shaped extension of the engagement portions 74 and 76 mayvary. In general they may each encompass a sector angle of up to about140°. However, this provides an undesired weight increase of thecoupling. The wider the engagement portions, the better will be theengagement of coupling. A compromise must therefore be made. A preferredsector angle for the engagement portion 74 is about 90°-100° and for theengagement portion 76 about 30°-50°.

To prevent the coupling grip from being completely lost if a faultoccurs in the hydraulic system serving the hydraulic cylinder 82, heretoo a suitable safety device is arranged to ensure that attachmentmembers 61, 62 cannot become separated from each other when such a faultoccurs. Such a safety device is then served by a drive system other thansaid hydraulic system.

A valuable effect obtained by designing all engagement surfaces with acircle arc-shaped extension in accordance with the present invention isthat the total engagement area is increased and it will be greater incomparison with engagement surfaces which are parallel with each otherfor a given width of the quick coupling. Conversely, the width of thequick coupling can be reduced for a given engagement area.

If desired, the two locking parts 21, 22; 71, 72 may each consist of twoseparate or connected parts.

I claim:
 1. A coupling means for detachably coupling a working implement(1) to the operating arm of an excavating machine, said implement havingan upper surface facing the operating arm, said coupling meanscomprising a first attachment member (11) which is rigidly mounted tothe upper surface of the implement (1) and comprises a coupling element(13), and a second attachment member (12) supported by the operating armstick (6) and operating cylinder (7) via horizontal, parallel shafts (8,9) and comprising a coupling element (15) consisting of two lockingparts (21, 22) arranged movable in relation to each other to be broughtinto locking engagement with the coupling element (13) of the firstattachment member (11) by means of a power-generating means (32), saidcoupling elements (13, 15) having cooperating engagement surfaces (17,25, 27) which, when the attachment members (11, 12) are connectedtogether, are located in a common reference plane (R) which isperpendicular to a common central plane for the stick (6) and operatingcylinder (7), characterised in that all engagement surfaces (17, 25, 27)of the two coupling elements (13, 15) have a circle arc-shaped extensionin said reference plane (R) and have the same radius.
 2. A couplingmeans according to claim 1, characterised in that said engagementsurfaces (17, 25, 27) are arranged in relation to each other in such amanner that they have the same centre when the attachment members (11,12) are connected together.
 3. A coupling means according to claim 1,characterised in that said second attachment member (12) comprises aconnection element (47) forming a rigid body, that one locking part (21)is rigidly attached to the connection element (47) and the other lockingpart (22) is movably arranged in the connection element (47) as alocking device, and that the engagement surfaces (17, 25, 27) areinclined in relation to said reference plane (R).
 4. A coupling meansaccording to claim 3, characterised in that the locking device (22) isarranged to be moved between a free-running position and a lockingposition in a rectilinear path.
 5. A coupling means according to claim4, characterised in that the coupling element (13) of the implementcomprises a circular engagement portion (16) with a circular engagementsurface (17).
 6. A coupling means according to claim 5, characterised inthat the circular engagement surface (17) of the coupling element (13)is formed on the outside of the engagement portion (16).
 7. A couplingmeans according to claim 5, characterised in that the circularengagement surface (66) of the coupling element (63) is formed on theinside of the engagement portion (65).
 8. A coupling means according toclaim 6, characterised in that the engagement surface of the couplingelement (13; 63) faces towards the upper side of the implement (1; 51).9. A coupling means according to claim 8, characterised in that thecoupling element (13) is in the form of a flat ring or plate.
 10. Acoupling means according to claim 9, characterised in that theattachment member (11) of the implement (1) comprises a distance element(14) secured to the lower side of the ring or plate (13), by means ofwhich the attachment member (11) is welded to the implement (1).
 11. Acoupling means according to any of claim 1, characterised in that theengagement surfaces (17, 25, 27) form an acute angle with said referenceplane (R) of 20°-60°, the engagement surfaces of the two attachmentmembers (11, 12) having the same angle in each individual case.
 12. Acoupling means according to any of claim 1, characterised in that theengagement surfaces (66, 75, 77) form an acute angle of 40°-80°, withsaid reference plane (R), the engagement surfaces of the two attachmentmembers (61, 62) having the same angle in each individual case.
 13. Acoupling means according to any of claims 1, characterised in that thelocking device (22; 72) encompasses a smaller sector angle than thestationary locking part (21; 71).
 14. A coupling means according toclaim 13, characterised in that the locking parts (21, 22) of theoperating arm attachment member (12) encompass sector angles ofapproximately 90°-100° and 20°-35°, respectively.
 15. A coupling meansaccording to claim 13, characterised in that the locking parts (71, 72)of the operating arm attachment member (62) encompass sector angles ofapproximately 90°-100° and 30°-50°, respectively.